- ID:
- ivo://CDS.VizieR/J/ApJS/229/30
- Title:
- Revised stellar properties of Q1-17 Kepler targets
- Short Name:
- J/ApJS/229/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The determination of exoplanet properties and occurrence rates using Kepler data critically depends on our knowledge of the fundamental properties (such as temperature, radius, and mass) of the observed stars. We present revised stellar properties for 197096 Kepler targets observed between Quarters 1-17 (Q1-17), which were used for the final transiting planet search run by the Kepler Mission (Data Release 25, DR25). Similar to the Q1-16 catalog by Huber+ (2014, J/ApJS/211/2), the classifications are based on conditioning published atmospheric parameters on a grid of Dartmouth isochrones, with significant improvements in the adopted method and over 29000 new sources for temperatures, surface gravities, or metallicities. In addition to fundamental stellar properties, the new catalog also includes distances and extinctions, and we provide posterior samples for each stellar parameter of each star. Typical uncertainties are ~27% in radius, ~17% in mass, and ~51% in density, which is somewhat smaller than previous catalogs because of the larger number of improved logg constraints and the inclusion of isochrone weighting when deriving stellar posterior distributions. On average, the catalog includes a significantly larger number of evolved solar-type stars, with an increase of 43.5% in the number of subgiants. We discuss the overall changes of radii and masses of Kepler targets as a function of spectral type, with a particular focus on exoplanet host stars.
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- ID:
- ivo://CDS.VizieR/J/ApJS/211/2
- Title:
- Revised stellar properties of Q1-16 Kepler targets
- Short Name:
- J/ApJS/211/2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present revised properties for 196468 stars observed by the NASA Kepler mission and used in the analysis of Quarter 1-16 (Q1-16; May 2009 to Dec 2012) data to detect and characterize transiting planets. The catalog is based on a compilation of literature values for atmospheric properties (temperature, surface gravity, and metallicity) derived from different observational techniques (photometry, spectroscopy, asteroseismology, and exoplanet transits), which were then homogeneously fitted to a grid of Dartmouth stellar isochrones. We use broadband photometry and asteroseismology to characterize 11532 Kepler targets which were previously unclassified in the Kepler Input Catalog (KIC). We report the detection of oscillations in 2762 of these targets, classifying them as giant stars and increasing the number of known oscillating giant stars observed by Kepler by ~20% to a total of ~15500 stars. Typical uncertainties in derived radii and masses are ~40% and ~20%, respectively, for stars with photometric constraints only, and 5%-15% and ~10% for stars based on spectroscopy and/or asteroseismology, although these uncertainties vary strongly with spectral type and luminosity class. A comparison with the Q1-Q12 catalog shows a systematic decrease in radii of M dwarfs, while radii for K dwarfs decrease or increase depending on the Q1-Q12 provenance (KIC or Yonsei-Yale isochrones). Radii of F-G dwarfs are on average unchanged, with the exception of newly identified giants. The Q1-Q16 star properties catalog is a first step toward an improved characterization of all Kepler targets to support planet-occurrence studies.
- ID:
- ivo://CDS.VizieR/J/A+A/448/1107
- Title:
- RI light curves of V1493 Aql
- Short Name:
- J/A+A/448/1107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Period analysis of CCD photometry of V1493 Aql (Nova Aql 1999 No. 1) performed during 12 nights through I and R filters a few weeks after maximum is presented.
- ID:
- ivo://CDS.VizieR/J/AJ/155/51
- Title:
- Robo-AO binary star systems in 3 open clusters
- Short Name:
- J/AJ/155/51
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We identify and roughly characterize 66 candidate binary star systems in the Pleiades, Praesepe, and NGC 2264 star clusters, based on robotic adaptive optics imaging data obtained using Robo-AO at the Palomar 60" telescope. Only ~10% of our imaged pairs were previously known. We detect companions at red optical wavelengths, with physical separations ranging from a few tens to a few thousands of au. A three-sigma contrast curve generated for each final image provides upper limits to the brightness ratios for any undetected putative companions. The observations are sensitive to companions with a maximum contrast of ~6^m^ at larger separations. At smaller separations, the mean (best) raw contrast at 2" is 3.8^m^ (6^m^), at 1" is 3.0^m^ (4.5^m^), and at 0.5" is 1.9^m^ (3^m^). Point-spread function subtraction can recover nearly the full contrast in the closer separations. For detected candidate binary pairs, we report separations, position angles, and relative magnitudes. Theoretical isochrones appropriate to the Pleiades and Praesepe clusters are then used to determine the corresponding binary mass ratios, which range from 0.2 to 0.9 in q=m_2_/m_1_. For our sample of roughly solar-mass (FGK type) stars in NGC 2264 and sub-solar-mass (K and early M-type) primaries in the Pleiades and Praesepe, the overall binary frequency is measured at ~15.5%+/-2%. However, this value should be considered a lower limit to the true binary fraction within the specified separation and mass ratio ranges in these clusters, given that complex and uncertain corrections for sensitivity and completeness have not been applied.
- ID:
- ivo://CDS.VizieR/J/AJ/156/259
- Title:
- Robo-AO detected close binaries in Gaia DR2
- Short Name:
- J/AJ/156/259
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use the Robo-AO survey of Kepler planetary candidate host stars, the largest adaptive optics survey yet performed, to measure the recovery rate of close stellar binaries in Gaia DR2 (Cat. I/345). We find that Gaia recovers binaries down to 1" at magnitude contrasts as large as six; closer systems are not resolved, regardless of secondary brightness. Gaia DR2 binary detection does not have a strong dependence on the orientation of the stellar pairs. We find 177 nearby stars to Kepler planetary candidate host stars in Gaia DR2 that were not detected in the Robo-AO survey, almost all of which are faint (G>20); the remainder were largely targets observed by Robo-AO in poor conditions. If the primary star is the host, the impact on the radii estimates of planet candidates in these systems is likely minimal; many of these faint stars, however, could be faint eclipsing binaries that are the source of a false positive planetary transit signal. With Robo-AO and Gaia combined, we find that 18.7+/-0.7% of Kepler planet candidate hosts have nearby stars within 4". We also find 36 nearby stars in Gaia DR2 around 35 planetary candidate host stars detected with K2. The nearby star fraction rate for K2 planetary candidates is significantly lower than that for the primary Kepler mission. The binary recovery rate of Gaia will improve initial radius estimates of future Transiting Exoplanet Survey Satellite planet candidates significantly; however, ground-based high-resolution follow-up observations are still needed for precise characterization and confirmation. The sensitivity of Gaia to closely separated binaries is expected to improve in later data releases.
- ID:
- ivo://CDS.VizieR/J/ApJ/888/34
- Title:
- Robo-AO Kepler asteroseismic survey. II.
- Short Name:
- J/ApJ/888/34
- Date:
- 25 Oct 2021 10:08:41
- Publisher:
- CDS
- Description:
- The Kepler Space Telescope observed over 15000 stars for asteroseismic studies. Of these, 75% of dwarfs (and 8% of giants) were found to show anomalous behavior, such as suppressed oscillations (low amplitude) or no oscillations at all. The lack of solar-like oscillations may be a consequence of multiplicity, due to physical interactions with spectroscopic companions or due to the dilution of oscillation amplitudes from "wide" (AO detected; visual) or spectroscopic companions introducing contaminating flux. We present a search for stellar companions to 327 of the Kepler asteroseismic sample, which were expected to display solar-like oscillations. We used direct imaging with Robo-AO, which can resolve secondary sources at ~0.15", and followed up detected companions with Keck AO. Directly imaged companion systems with both separations of <=0.5" and amplitude dilutions >10% all have anomalous primaries, suggesting these oscillation signals are diluted by a sufficient amount of excess flux. We also used the high-resolution spectrometer ESPaDOnS at the Canada-France-Hawai'i Telescope to search for spectroscopic binaries. We find tentative evidence for a higher fraction of spectroscopic binaries with high radial velocity scatter in anomalous systems, which would be consistent with previous results suggesting that oscillations are suppressed by tidal interactions in close eclipsing binaries.
- ID:
- ivo://CDS.VizieR/J/AJ/152/18
- Title:
- Robo-AO Kepler planetary candidate survey. II.
- Short Name:
- J/AJ/152/18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We initiated the Robo-AO Kepler Planetary Candidate Survey in 2012 to observe each Kepler exoplanet candidate host star with high angular resolution, visible light, laser adaptive optics (AOs) imaging. Our goal is to find nearby stars lying in Kepler's photometric apertures that are responsible for the relatively high probability of false-positive exoplanet detections and that cause underestimates of the size of transit radii. Our comprehensive survey will also shed light on the effects of stellar multiplicity on exoplanet properties and will identify rare exoplanetary architectures. In this second part of our ongoing survey, we observed an additional 969 Kepler planet candidate hosts and we report blended stellar companions up to {Delta}m{approx}6 that contribute to Kepler's measured light curves. We found 203 companions within ~4'' of 181 of the Kepler stars, of which 141 are new discoveries. We measure the nearby star probability for this sample of Kepler planet candidate host stars to be 10.6%+/-1.1% at angular separations up to 2.5'', significantly higher than the 7.4%+/-1.0% probability discovered in our initial sample of 715 stars; we find the probability increases to 17.6%+/-1.5% out to a separation of 4.0''. The median position of Kepler Objects of Interest (KOIs) observed in this survey are 1.1{deg} closer to the galactic plane, which may account for some of the nearby star probability enhancement. We additionally detail 50 Keck AO images of Robo-AO observed KOIs in order to confirm 37 companions detected at a <5{sigma} significance level and to obtain additional infrared photometry on higher significance detected companions.
- ID:
- ivo://CDS.VizieR/J/AJ/153/66
- Title:
- Robo-AO Kepler Planetary Candidate Survey. III.
- Short Name:
- J/AJ/153/66
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Robo-AO Kepler Planetary Candidate Survey is observing every Kepler planet candidate host star with laser adaptive optics imaging to search for blended nearby stars, which may be physically associated companions and/or responsible for transit false positives. In this paper, we present the results of our search for stars nearby 1629 Kepler planet candidate hosts. With survey sensitivity to objects as close as ~0.15", and magnitude differences {Delta}m=<6, we find 223 stars in the vicinity of 206 target KOIs; 209 of these nearby stars have not been previously imaged in high resolution. We measure an overall nearby-star probability for Kepler planet candidates of 12.6%+/-0.9% at separations between 0.15" and 4.0". Particularly interesting KOI systems are discussed, including 26 stars with detected companions that host rocky, habitable zone candidates and five new candidate planet-hosting quadruple star systems. We explore the broad correlations between planetary systems and stellar binarity, using the combined data set of Baranec et al. (2016, J/AJ/152/18) and this paper. Our previous 2{sigma} result of a low detected nearby star fraction of KOIs hosting close-in giant planets is less apparent in this larger data set. We also find a significant correlation between detected nearby star fraction and KOI number, suggesting possible variation between early and late Kepler data releases.
- ID:
- ivo://CDS.VizieR/J/ApJ/799/4
- Title:
- Robo-AO observations of binary stars
- Short Name:
- J/ApJ/799/4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We conducted a survey of nearby binary systems composed of main sequence stars of spectral types F and G in order to improve our understanding of the hierarchical nature of multiple star systems. Using Robo-AO, the first robotic adaptive optics instrument, we collected high angular resolution images with deep and well-defined detection limits in the Sloan Digital Sky Survey i' band. A total of 695 components belonging to 595 systems were observed. We prioritized observations of faint secondary components with separations over 10" to quantify the still poorly constrained frequency of their subsystems. Of the 214 secondaries observed, 39 contain such subsystems; 19 of those were discovered with Robo-AO. The selection-corrected frequency of secondary subsystems with periods from 10^3.5^ to 10^5^ days is 0.12+/-0.03, the same as the frequency of such companions to the primary. Half of the secondary pairs belong to quadruple systems where the primary is also a close pair, showing that the presence of subsystems in both components of the outer binary is correlated. The relatively large abundance of 2+2 quadruple systems is a new finding, and will require more exploration of the formation mechanism of multiple star systems. We also targeted close binaries with periods less than 100 yr, searching for their distant tertiary components, and discovered 17 certain and 2 potential new triples. In a subsample of 241 close binaries, 71 have additional outer companions. The overall frequency of tertiary components is not enhanced, compared to all (non-binary) targets, but in the range of outer periods from 10^6^ to 10^7.5^ days (separations on the order of 500AU), the frequency of tertiary components is 0.16+/-0.03, exceeding the frequency of similar systems among all targets (0.09) by almost a factor of two. Measurements of binary stars with Robo-AO allowed us to compute first orbits for 9 pairs and to improve orbits of another 11 pairs.
- ID:
- ivo://CDS.VizieR/J/ApJ/804/30
- Title:
- Robo-AO observed cool subdwarf companions
- Short Name:
- J/ApJ/804/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cool subdwarfs are the oldest members of the low-mass stellar population. Mostly present in the galactic halo, subdwarfs are characterized by their low-metallicity. Measuring their binary fraction and comparing it to solar-metallicity stars could give key insights into the star formation process early in the Milky Way's history. However, because of their low luminosity and relative rarity in the solar neighborhood, binarity surveys of cool subdwarfs have suffered from small sample sizes and incompleteness. Previous surveys have suggested that the binary fraction of red subdwarfs is much lower than for their main-sequence cousins. Using the highly efficient Robo-AO system, we present the largest high-resolution survey of subdwarfs, sensitive to angular separations ({rho}>=0.15") and contrast ratios ({Delta}_mi_<=6) invisible in past surveys. Of 344 target cool subdwarfs, 43 are in multiple systems, 19 of which are newly discovered, for a binary fraction of 12.5+/-1.9%. We also discovered seven triple star systems for a triplet fraction of 2.0+/-0.8%. Comparisons to similar surveys of solar-metallicity dwarf stars gives a ~3{sigma} disparity in luminosity between companion stars, with subdwarfs displaying a shortage of low-contrast companions. We also observe a lack of close subdwarf companions in comparison to similar-mass dwarf multiple systems.
